Method of relief grinding cutter blades



June 18, 1940. E. WILDHABER 2,204,714

METHOD OF RELIEF GRINDING CUTTER BLADES Original Filed May 20, 1955 2SheetsSheet 1 Zhmentor Ernesi T/VL'Zd/zczber (Ittorneg June 18, 1940. E.WILDHABER 4 METHOD OF RELIEF GRINDING CUTTER BLADES 4 Original Filed May20, 1955 2 Sheets-Sheet 2 Zhwentor Ernesi M/iZdZzQZver attorney PatentedJune 18, 1946 1 UNITED STATES PATENT OFFICE METHOD OF RELIEF GRINDINGCUTTER.

BLADES Ernest Wildhaber, Irondequoit, N. Y., assignor to Gleason Works,Rochester, N. Y., a corporation of New York Original application .May20, 1935, Serial No. 22,304. Divided and this application October 29,1937, Serial No. 171,712 s 7 Claims. (Cl. 515-288) The present inventionrelates to face-mill gear tween the wheel and head axially of the headas cutters and to their manufacture. The invention each blade passesacross the wheel. Blades recomprises a novel form of cutter, a novelmethod lief-ground in this way are correct. of sharpening the same and anovel methodand The first two methods of relief-grinding denovelapparatus for relief grinding the blades of scribed are suitable onlyfor relief-grinding the 5 face-mill gear cutters. This application is ablades of inserted-blade type gear cutters. division of my copendingapplication, Serial No. Neither method can be used for the relief-grind-22,304, filed May 20, 1935, and which is now i of des of segmental orring-type cutters or Patent No. 2,129,077. The. present application ofcutters whose blades are integral with the 10 is confined to the novelmethod and apparatus cutter head. The third described method may 10 forrelief-grinding the blades of face-mill gear be used for the grinding ofblades of these diiiertt r r ent types of cutters, but it has thedisadvantage Various methods have heretofore been used for in such casesthat the sides of the blades a relief-grinding the blades of face-millgear cutbe relief-ground back only a relatively short dist In one th thm d s t beground are tance because of the necessity of preventing the 15mounted in a dummy head so that they are tilted wheel from interferingwith one blade of a cutter out of cutting position and their relievedtop Whenit s grinding another b ade of the cutter. surfaces lie in aplane perpendicular to the axis Hence the blades have only a relativelyshort of the dummy head. The top and side surfaces of useful life, Thepossibility of interference arises the blades may then be ground byrotating a because of the reciprocating motion employed for 2 grindingwheel in engagement with the blades l the relief-grinding.

while rotating the dummy head on itsaxis to Cutters having a pluralityof blades integral pass the different blades successively across theWith one another have comemore and more into a wheel. When the bladesare returned to their use i recent y s, especially segmental and ownhead and mounted in erect position, they a ring type cutters.

will have the desired side and top cutting clear,- 1 The P y j t o e. pesent invention ance. With this method, both sides and the tops is, 50 pv e a e od of l e -grinding which of the blades maybe relief groundsimultaneousl W be Sui b relief-grinding the side sur- 1y. The pressureangles-of the sides of the blades faces of t e de o Segmental and ringtype will change, however, from ,front to rear and face-mill gearcutters and of cutters whose blades 30 hence blades ground by thismethod are only suitare integral with the cutter head. able for use inrough cutting. A further object of the invention is to provide Inanother method, the blades to be ground are a method for grinding therelieved side surfaces also mounted ina dummyhead but in this case, ofsegmental and ring type cutters and of cutters the blades are adjustedsidewise relative to the Whose blades are integral with the cutter head1 positions which they occupy during cutting, by which will permit ofrelief-grinding the whole of 35 the amount of clearance angle which itis desired the side surfaces of the blades from front to rear. to grindon the sides. of the blades. The relief- Still another object of theinvention is to progrinding operation then, is effected by rotating videa method forrelief-grinding the blad of the grinding wheel in engagementwith the blades face-mill gear cutters which may be employed s 40 whilerotating the dummy head on its axis to in the grinding of the blades ofany cutters of carry the different blades successively across the thistype and which will produce blades having grinding wheel. This method ofrelief grinding side surfaces of correct pressure angle throughrequiresthree dummy heads, one for the top and out their life. s one each forthe two sides of the blades. The Other objects of the invention will beapparent 45 method is accurate, however, and blades ground hereinafterfrom the specification and from the by this method may, therefore, beemployed for recital of the appended claims. finismcuttmg I V a In threlief grinding process of the present In still another prior method ofrelief-grinding invention, segmental cutting blades or the blades theblades of face-mill, gear cutters, the blades of a cutting ring maybeground with the seg- 50 are ground in their own heads and thereliefments or the ring secured to their head. It is grinding iseffected by rotating a grinding wheel preferred, however, to grind theinside surfaces of in engagement with the blades while rotating the sthe blades in a dummy head. For the relieving head on its axis and whilesimultaneously efprocess, a grinding wheel is used which has an 65iecting a relative reciprocating movement beoperating profile ofcircular arcuate shape. The

grinding Wheel is so dressed or positioned relative to a blade thatthecenter of its operating. profile is offset from the center of thesegment or ring or head in which the blade is secured. The

grinding wheel is' then rotated and reciprocated relative to the bladealong an element of one side surface of the blade. If the side surfaceof the blade'is of straight profile, and of positive pressure angle, aside surface will be ground on the blade which is cylindrical and whoseis offset from and inclined to the axis of the segment or ring or head.Thus, cutting clearance will be produced on the side surface of theblade. When one blade has been ground, the grindingwheel is withdrawnfrom engagement with the blade and the head is indexed to bring anotherblade into operative position to be ground. For the outside surfaces ofthe blades, a'grinding wheel of concave profile is used'and for theinside sur faces of the blades, a grinding wheel of convex profile shapeis used.

In the drawings: v Fig. 1 is a plan view of a face-mill gear cutterhaving its cutting blades formed in an-integral ring, and such as may berelief-ground with advantage by the method of the present invention;

, Fig. 7 is a plan view of a machine built according to oneembodiment ofthis invention for grind-' ing the cutting clearance on the sides ofblades of a face-mill gear cutter. V

Figs. 1 and 2 show one type of face-mill gear cutter whose blades may berelief ground with advantage by the method of the present invention..The cutter, which is designated at 23, has its cutting'portion in theform of a continuous, closed ring. The body portion of this ring isformed with an internal conical surface 22 to fit the tapered nose 23 orcutter head of the cutter spindle 2d of the gear cutting machine onwhich the cutter is to be used and the ring may also be formed with anexternal conical surface it for a purpose which will hereinafter appear.The cutting portion of the ring is formed with the cutting portion ofthe ring. Thispermits the cutting teeth to be readily sharpened.

To'provide cutting clearance, the tops 25 and the sides 2? and 28 of thecutting blades 25 are relieved back of the front faces 2% of the blades.

Figs. 3 and 4 show how the inside surfaces 28 of the teeth. 25 may berelief-ground by the process of the present invention. For this purposea grinding Wheel 35 is employed that has a convex operating surface 35of circular arcuate shape. The grinding wheel is so dressed or posi.tioned relative to a blade that the center??? of the arc 36 is offsetfrom the center 38 of the side surface 2% of the blade.

surface is ground on the inside of the blade that cutting ring. Thegrinding wheel 35 is then re-' ciprocated relatively along an element ofthe side surface 28 of the blade, as indicated by the arrow Intheinstance shown, the inside surfaces of the blades of the cutter areof straight profile. Hence, as the rotating grinding wheel isreciprocated up and down the side surface of the blade in the directionof the arrow 32%, it will grind a cylindrical,- side surface on theblade whose axis is offset from the axis of the cutter and passesthroughthe center 3? of curvature of the wheel anldis'inclined to theaxis of the cutter at an angle corresponding to the pressure angle ofthe is non-radial of the axis of the cutter and has clearance relativeto the inside cutting edge of the blade.

When the inside surface of one blade of the cutter has been ground, thewheel is withdrawn from engagement with the cutter and the cutter isindexed to bring the next cutting blade into position to be ground. I a

The method of grinding the outside surfaces 27 of the blades isillustrated in Figs. 5 and 6. Here a grinding wheel id is employed thathas a concave operating surface ll which is of circular arcuate shape.In the grinding operation, the grinding wheel is sodressed or positionedrelative to a blade'of the cutter that the center 62 of the profile ofthe Wheel is offset from the axis Ziiiof the cutter. In the grindingoperation, the grinding wheel is rotated on its axis and simultaneouslymoved relative to the cutter along an element of the outside surface 2?.In the grinding of a cutting blade straight profile, the grinding wheelis reciprocated along a straight line element of the outside surface 2?in the direction of the arrow M and thus an outside surface Zl'will beground upon the cutting blade which has cutting clearanceback of theoutside cutting edge of the blade and which is a cylindrical surfacewhose axis passes through the center 62 of curvature of the wheel and isinclined to and offset from the axis of the cutter. As before, after thesidesurface of one blade of the cutter .has been ground, the grindingwheel is moved clear of the cutter and the cutter is indexed to bringanother blade into grinding positionf When the radii of the cylindricalsurfaces ground on the sides of the blades according to the method'ofthe present invention are properly selected-the cylindrical surfaceswill approximate very closely helical surfaces ground by the prior axialrelief grinding method or to the conical surfaces ground by the knownofiset grinding method. k

In grinding the inside surfaces of the cutting blades, it is preferableto use a special head such as shown at 45 in Fig. 3 in order to hold thecutting blades to be ground. The blades or the cutting segment or thecutting ring ischucked in this head by the outside surface 46 of itsbody portion which may be groundfslightly conical to fit an internalconical surface formed on the head (35. The head 55 holds the blades orsegment or ring, as the case may be, securely and permits free movementof the grinding wheel .to grind the inside surfacesof the cutting bladesfrom the top to the bottom thereof. This same head may be used, ifdesired, in grinding the outside surfaces of the blades, or they may beground in their own head. By means of the In this way, a side 2,204,714present invention, all the cutting teeth of a segmental cutter or of aring type cutter may have their side surfaces ground for their fulllength from front to rear and, moreover, these surfaces may be groundaccurately with reference to their common axis of rotation. i

In Figs. 4 and 6, the blade being operated upon is shown in section in aplane perpendicular to the axis of the cutter.

One form ofmachine for grinding the cutting clearances on the sides ofcutting blades by the process of the present invention is .shown in Fig.7. 50 designates the base or frame of this machine. The'cutter 2fl,'whicl1 isto be ground, is

. secured in any suitable manner to the work spindle 52 of this machine.Thework spindle is journaled in suitable bearings inthe work head 53which is adjustable axially ofthe spindle on ways 54 thatare formed onthe upper surface of a rotary turret or table 55. The turret or table 55is mounted for rotatable adjustment upon a slide 56 that is laterallyadjustable upon the base 50 of the machine. ,The bolts51 which engageinthe T-slots 58, that are formed in the base ll, serve to secure theslide 5B in any position of its lateral adjustment. The grinding wheel Wis journaled in the projecting arm 60 of the slide 6| on which ismounted the motor 62 that drives the grinding wheel. The motor isconnected to the grinding wheel by the pulleys 63 and 64 and the belt65. e The slide 6| is vertically adjustable. upon the column 61 of acarriage 68 that is slidable on ways 69 formed on the base of themachine. The slide 6| can be adjusted vertically on the column 61 byrotation of the screw shaft 10. e

The carriage 68 is'reciprocated by a cam 12 which is secured to a shaftthat is rotatably mounted in the base of the machine. A roller, which iscarried by a bracket 14, engages in the track 13 of this cam. Thebracket 14 is secured to the carriage 68 by screws 15.

The cam 72 imparts a reciprocating movement,

a return, to withdraw the grinding wheel from";

operating position, retain it out of operating position during indexingand return it to operating position again after the indexing has beencompleted. The index mechanism for the work spindle may be of anysuitable type. Preferably, a

notched plate type of index mechanism will be employed. The plate ofsuch a mechanism is shown at 16.

Whengrinding the outside surfaces of cutting blades, a concave grindingwheel such as shown at will be employed, while when grinding the insidesurfaces of the cutting blades, a convex type of grinding wheel such asshown at 35 will be used. The angular adjustment of the table 55 permitsof setting the cutter to the pressure angle of the side surfaces to beground on the cutting teeth. The lateral adjustment of the slide 56allows of moving the cutter head to one side or the other of thegrinding Wheel depending upon whether the outside or the inside surfacesof the cutting blades are to be ground. The

vertical adjustment of the slide 6| upon'thecolmph 6'! permits ofoffsetting the center of the operating'profile of the grinding wheelrelative to the axis of the cutter so as to grind the side surfaces ofthe cutting teeth with the desired cutting clearance.

In operationythe work isheld stationary and the grinding wheel isrotated continuously on its axis from the motor 62 while beingsimultaneously reciprocated up and down the side surface of a cuttingblade by the cam 12. After a series of short strokes, the wheel iswithdrawn from engagement with the cutter by action of the cam 12, thework spindle is indexed to bring the next blade into position to beground, and then the wheel is returned into operative position.

While the inventionhas, been described inconnection with particularembodiments thereof, it is capable of various further embodiments andthis application is intended to cover any variations, uses, oradaptations of the invention following, in general, the principles ofthe invention and including such departures from the present disclosureas come within known or customary practice in the art to which theinvention pertains and as may be applied to the essential featureshereinbefore set forth and as fall within the scope of the invention orthe limits of the appended claims.

Having thus described claim is: e 1. The method of grinding clearance onthe side surface of a face-mill gear cutter blade back of itsside-cutting edge which comprises mounting the blade on a rotary head,positioning a grinding wheel whose operating surface is of curvedprofile in engagement with the described side-surface of the blade sothat the curved surface of the Wheel is inclined to a circle, whichpasses through the side-cutting edge of the blade and is concentric withthe head, at an angle corresponding to the angle of side clearance to bemy invention, what I ground on the blade, rotating the wheel in enxgagement with the blade while, producing a relative reciprocatingmovement between the wheel and blade along a line element of the sidesurface of the blade, and periodically indexing the head to bringsuccessive blades into grinding position.

2. The method of grinding side clearance on the outside surface of aface-mill gear cutter blade which comprises mounting the blade inarotary head, positioning a grinding wheel whose operating surface is ofconcave profile, in engagement with the said surface of the blade sothat the wheel profile extends in the general direction of the length ofthe blade and a radius of curvature of the wheel intersects a radius ofthe head at an angle equal to the clearance angle to be ground on theside surface of the blade, rotating the wheel onits axis and producing arelative reciprocating movement between the wheel and head along a lineelement of the side surface of the blade.

3. The method of grinding side clearance on the inside surface of aface-mill gear cutter blade whose inside surface is a surface ofrevolution, which comprises mounting the blade in a rotary head,positioning a grinding wheel whose operating surface is of convexprofile in an axial plane in engagement with the inside surface of theblade so that the profile of the operating surface of the wheel extendsin the general direction of the length of the blade and the center ofcurvature of the profile of said operating surface is offset from theaxis of the head a distance determined by the clearance angle to beground on the inside surface of the blade, rotating the wheel on itsaxis and producing a relative reciprocating movement between the wheeland head in the direction of the height of the blade profile along aline element of the inside surface of the blade.

4. A machine for grinding cutting clearance on a side surface of aface-mill'gear cutter blade comprising a work support, a wheel support,a rotary grinding wheel mounted on the wheel support and having anoperating portion which is of curved profile, means for positioning thegrinding wheel in operative engagement with a side surface of the bladeto be ground, means for rotating the grinding wheel on its axis, meansfor reciprocating'the grinding wheel relative to the work in thedirection of a line element of the side surface of a blade through aseries ofshort strokes followed periodically by a movement of a longerstroke, and means for indexing the work support on the long strokesofthe grinding wheel when the wheel is clear of the work.

5. The method of grinding side clearance on a gear cutter which hasblades projecting from a i body portion in the general direction of theaxis I: eral direction of the len t of the blade; in

tating the grinding wheel and in providingbodily relative motion betweenthe grinding wheel and the cutter in the generaldirection of the heightof said side surface.

6. The method of grinding s de clearance on a gear cutter whichhasbladesprojecting from a body portion in the general direction of theaxis of the cutter, which consists in vmounting a grinding wheel havinga curved profile inan axial section in engagement with a side surface ofa blade so that the wheel-profile extends in the general direction ofthe length of the blade, in rotating the grinding wheel, and inproviding bodily relativemotion between the wheel and cutter in adirection perpendicular to the axis of the wheel.

'7. The method of grinding side clearance on the inside and outsidesurfaces of face-mill gear cutter blades which comprises grinding theinside and outside surfaces of the blades with separate grinding wheels,each of which has an active surface of circular arcuate profile in anaxial plane, by positioning each wheel in engagement with a side surfaceof a blade of the cutter so that the profile of the wheel extends in'the general direction of the length of the blade from front to rear, androtating the wheel on its axis while producing a relative movementbetween the wheel and blade in the direction of the profile of theblade, and periodically indexing the cutter to bring successive bladesinto grinding position, the wheel used for grinding the outside surfacesof the blades ERNEST WILDHABER.

